scyther/src/match_basic.c

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/*!\file match_basic.c
*\brief Implements the match function.
*
* The match function here is integrated here with an enabled() function.
* It is also the basic match, so not suited for Constraint Logic Programming.
*/
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#include <stdlib.h>
#include <stdio.h>
#include "memory.h"
#include "substitution.h"
#include "system.h"
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#include "modelchecker.h"
#include "match_basic.h"
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//! Get the candidates list for typeless basic stuff
__inline__ Termlist
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candidates (const Knowledge know)
{
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return knowledgeGetBasics (know);
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}
struct fvpass
{
int (*solution) ();
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System sys;
int run;
Roledef roledef;
int (*proceed) (System, int);
};
//! Fix variables in a message, and check whether it can be accepted.
/**
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* fp.sys is only accessed for the matching type.
*@returns 1 (true) if there exists a message that can be accepted, fvpass returns 1 on it.
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*/
int
fixVariablelist (const struct fvpass fp, const Knowledge know,
Termlist varlist, const Term message)
{
int flag = 0;
Termlist tlscan;
Termlist candlist;
if (varlist != NULL)
{
if (!isTermVariable (varlist->term))
{
while (varlist != NULL && !isTermVariable (varlist->term))
{
varlist = varlist->next;
}
}
}
/* cond: varlist == NULL || isTermvariable(varlist->term) */
if (varlist == NULL)
{
/* there are no (more) variables to be fixed. */
/* actually trigger it if possible */
int copied;
Knowledge tempknow;
/* first we propagate the substitutions in the knowledge */
/* TODO this must also be done for all agent knowledge!! */
if (knowledgeSubstNeeded (know))
{
copied = 1;
tempknow = knowledgeSubstDo (know);
}
else
{
copied = 0;
tempknow = know;
}
if (inKnowledge (tempknow, message))
{
if (fp.solution != NULL)
{
flag = fp.solution (fp, tempknow);
}
else
{
/* signal that it was enabled, now we omit the pruning */
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flag = 1;
}
}
else
{
/* not enabled */
flag = 0;
}
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/* restore state */
if (copied)
{
knowledgeDelete (tempknow);
knowledgeSubstUndo (know);
}
return flag;
}
/* cond: isTermvariable(varlist->term) */
varlist->term = deVar (varlist->term);
/* cond: realTermvariable(varlist->term) */
candlist = candidates (know);
#ifdef DEBUG
if (DEBUGL (5))
{
indent ();
printf ("Set ");
termPrint (varlist->term);
printf (" with type ");
termlistPrint (varlist->term->stype);
printf (" from candidates ");
termlistPrint (candlist);
printf ("\n");
}
#endif
/* Now check all candidates. Do they work as candidates? */
tlscan = candlist;
while (tlscan != NULL && !(flag && fp.solution == NULL))
{
if (!isTermEqual (varlist->term, tlscan->term))
{
/* substitute */
varlist->term->subst = tlscan->term;
if (validSubst (fp.sys->match, varlist->term))
{
#ifdef DEBUG
if (DEBUGL (5))
{
indent ();
printf ("Substituting ");
termPrint (varlist->term);
printf ("\n");
}
#endif
/* now we may need to substitute more */
flag = fixVariablelist (fp, know, varlist->next, message)
|| flag;
}
}
tlscan = tlscan->next;
}
/* restore state: variable is not instantiated. */
varlist->term->subst = NULL;
/* garbage collect */
termlistDelete (candlist);
return flag;
}
/*
* check whether a roledef, given some newer knowledge substitutions, can survive
*/
#define enabled_basic(sys,know,newterm) !inKnowledge(know,newterm)
//! Try to execute a read event.
/**
* Try to execute a read event. It must be able to be construct it from the
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* current intruder knowledge (Inject), but not from the forbidden knowledge
* set, which we tried earlier.
*
*@returns 0 if it is not enabled, 1 if it was enabled (and routes explored)
*\sa explorify()
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*/
int
matchRead_basic (const System sys, const int run,
int (*proceed) (System, int))
{
Roledef rd;
int flag = 0;
struct fvpass fp;
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Termlist varlist;
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int solution (struct fvpass fp, Knowledge know)
{
Knowledge oldknow;
Term newterm;
/* remove variable linkages */
newterm = termDuplicateUV (fp.roledef->message);
/* a candidate, but if this is a t4 traversal, is it also an old one? */
if (fp.sys->traverse < 4 ||
fp.roledef->forbidden == NULL ||
enabled_basic (fp.sys, fp.roledef->forbidden, newterm))
{
/* it is possibly enabled, i.e. not forbidden */
int enabled;
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oldknow = fp.sys->know;
fp.sys->know = know;
#ifdef DEBUG
if (DEBUGL (5))
{
printf ("+");
}
#endif
enabled = fp.proceed (fp.sys, fp.run); // flag determines the enabled status now
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fp.sys->know = oldknow;
termDelete (newterm);
return enabled;
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}
else
{
/* blocked */
#ifdef DEBUG
if (DEBUGL (5))
{
printf ("-");
}
#endif
termDelete (newterm);
return 0;
}
}
rd = runPointerGet (sys, run);
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varlist = termlistAddVariables (NULL, rd->message);
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fp.sys = sys;
fp.run = run;
fp.roledef = rd;
fp.proceed = proceed;
fp.solution = solution;
#ifdef DEBUG
if (DEBUGL (5))
{
indent ();
printf ("{\n");
}
#endif
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flag = fixVariablelist (fp, sys->know, varlist, rd->message);
termlistDelete (varlist);
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#ifdef DEBUG
if (DEBUGL (5))
{
indent ();
printf ("} with flag %i\n", flag);
}
#endif
return flag;
}
//! Skip an event
/**
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* Skips over an event. Because the intruder knowledge is incremental, we can
* just overwrite the old value of forbidden.
*@returns 1
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*/
int
block_basic (const System sys, const int run)
{
Knowledge pushKnow;
Roledef rd;
rd = runPointerGet (sys, run);
pushKnow = rd->forbidden;
rd->forbidden = sys->know;
traverse (sys);
rd->forbidden = pushKnow;
return 1;
}
//! Execute a send
/**
*@returns 1
*/
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int
send_basic (const System sys, const int run)
{
Roledef rd = runPointerGet (sys, run);
/* execute send, push knowledge? */
if (inKnowledge (sys->know, rd->message))
{
/* no new knowledge, so this remains */
explorify (sys, run);
}
else
{
/* new knowledge, must store old state */
Knowledge oldknow = sys->know;
sys->know = knowledgeDuplicate (sys->know);
sys->knowPhase++;
knowledgeAddTerm (sys->know, rd->message);
explorify (sys, run);
sys->knowPhase--;
knowledgeDelete (sys->know);
sys->know = oldknow;
}
return 1;
}